The UK's most complete GLP-1 guide
Every Question Answered. Every Side Effect Explained.
- How GLP-1 medications work
- Mounjaro vs Wegovy compared
- Injection instructions
- Side effects & solutions
- What to eat on treatment
- FAQs answered
Free tracker included with every download this week
How Does Mounjaro Subscription Work in the UK?
Mounjaro (tirzepatide) is a prescription-only weight loss injection available in the UK through both NHS specialist services and private online prescribing. Unlike a traditional subscription, Mounjaro is prescribed as a series of once-weekly injections delivered in KwikPen devices, with doses increasing gradually over several months. Understanding how UK subscription and access models work will help you explore whether this GLP-1 medication is right for your weight management journey.
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Calculate Your BMI Instantly
Enter your height and weight below. Supports both imperial (stone & lbs) and metric (kg). Results include NHS category, healthy weight range, and ethnicity adjustments.
What Is BMI and Why Does It Matter?
Body Mass Index (BMI) is the most widely used screening tool for assessing whether your weight falls within a healthy range. Used by the NHS, GPs, and weight management services across the UK, BMI provides a quick snapshot of your weight relative to your height. The formula is simple: your weight in kilograms divided by your height in metres squared (kg/m²).
While BMI isn't a perfect measure — it doesn't account for muscle mass, bone density, or fat distribution — it remains the standard first step in identifying potential weight-related health risks including type 2 diabetes, cardiovascular disease, high blood pressure, and certain cancers.
The NHS also recommends adjusted thresholds for people of South Asian, Chinese, or Black African heritage — a BMI of 23 or above is classified as overweight, and 27.5 as obese. Our calculator includes this adjustment as a one-click toggle.
How Mounjaro Prescription Access Works in the UK
NHS access: Mounjaro is available through NHS tier 3 specialist weight management services following NICE approval. You'll need a GP referral to access NHS specialist services in your area. Availability varies significantly by region, and waiting lists can be lengthy—sometimes several months to over a year depending on your local integrated care board (ICB). Once accepted into an NHS programme, your prescriber will manage your care, including dose titration and monitoring.
Private access: You can access Mounjaro privately through GPhC-registered online prescribing services without an NHS referral. These services operate on a subscription or pay-per-prescription basis. You'll complete an online clinical assessment, and if approved by a UK-licensed prescriber, your prescription is dispensed by a registered pharmacy. Private access is typically faster—often within days—but involves ongoing costs ranging from approximately £129–£320 per month depending on your dose.
- NHS: free at point of use, but subject to regional availability and waiting lists
- Private: faster access, but you pay for each prescription or subscription
- Both routes require a clinical assessment to confirm eligibility
Clinically BackedWeight Loss
No appointments. No waiting rooms. Just care — from a UK-regulated online pharmacy.
How It Works
Three simple steps to understand your weight and take action.
Enter your height and weight in our free calculator. Get your BMI, NHS category, healthy weight range, and ethnicity-adjusted thresholds instantly.
If your BMI suggests you're overweight or obese, explore our GLP-1 calculators to project potential weight loss on Mounjaro or Wegovy.
Use our progress tracker to log your weight weekly, visualise your journey with charts, and stay motivated — all stored privately in your browser.
Free Weight Loss Tools & Guides
Everything you need to understand your weight, explore medication options, and track your progress — completely free.
Managing Your Mounjaro KwikPen Doses
Mounjaro comes as a pre-filled KwikPen device—each pen contains four weekly injections. Your prescriber will start you at 2.5 mg weekly and increase the dose gradually: 5 mg, 7.5 mg, 10 mg, 12.5 mg, and finally 15 mg (the maximum dose). You'll spend a minimum of four weeks on each dose before escalating. Each KwikPen lasts one month, so ordering or refilling happens monthly. You inject once weekly on the same day each week, rotating injection sites between your stomach, thigh, and upper arm. Store unopened pens in the fridge at 2–8°C, and keep them in the original carton.
If you're accessing Mounjaro privately, your provider will typically offer automatic monthly refills or on-demand ordering. If accessing via NHS, your specialist service will manage your prescription and dose adjustments at scheduled appointments. Use our GLP-1 weight loss calculator to project potential results at different Mounjaro doses alongside diet and exercise changes.
When considering Mounjaro subscription options, eligibility is assessed individually. You typically qualify if you have a BMI of 30 or above, or 27–29.9 with a weight-related health condition such as type 2 diabetes, high blood pressure, or sleep apnoea. For people of South Asian, Chinese, Black African, or Black Caribbean heritage, lower BMI thresholds may apply (from BMI 27.5). Pregnant or breastfeeding individuals cannot take Mounjaro. Clinical trials showed that on average, people taking Mounjaro lost 15–21% of their body weight over 72 weeks alongside a reduced-calorie diet and increased physical activity—though individual results vary significantly. Your prescriber will assess whether Mounjaro is suitable for you based on your personal health history and current medications.
- Dual GIP/GLP-1 receptor agonist
- Up to 22.5% body weight loss (SURMOUNT-1)
- Weekly injection, dose escalation over 20+ weeks
- Available via private prescription in the UK
- Doses: 2.5mg → 5mg → 7.5mg → 10mg → 12.5mg → 15mg
- GLP-1 receptor agonist
- Up to 15–17% body weight loss (STEP trials)
- Weekly injection, 5-step dose escalation
- NHS & private prescription available
- Doses: 0.25mg → 0.5mg → 1mg → 1.7mg → 2.4mg
Mounjaro vs Wegovy: Head-to-Head
A side-by-side comparison of the two most popular GLP-1 weight loss medications available in the UK.
| Feature | Mounjaro | Wegovy |
|---|---|---|
| Drug class | Dual GIP/GLP-1 agonist | GLP-1 agonist |
| Active ingredient | Tirzepatide | Semaglutide |
| Avg. weight loss | 15–22.5% | 12–17% |
| Key trial | SURMOUNT-1 (2022) | STEP 1 (2021) |
| Max dose | 15 mg weekly | 2.4 mg weekly |
| Escalation period | 20–32 weeks | 16–20 weeks |
| Administration | Weekly injection (pen) | Weekly injection (pen) |
| NHS availability | Private prescription only | NHS & private |
| Approx. private cost | £150–£250/month | £150–£300/month |
| Common side effects | Nausea, diarrhoea, constipation | Nausea, vomiting, diarrhoea |
Data sourced from SURMOUNT-1 and STEP 1 clinical trials. Costs are approximate and vary by provider. Always consult a prescriber.
Am I Eligible for Weight Loss Medication?
In the UK, eligibility for GLP-1 weight loss medications like Mounjaro and Wegovy is based on your BMI and overall health profile.
- BMI of 30 or above (obese)
- Age 18 or over
- No contraindicated conditions
- Committed to lifestyle changes
- BMI of 27 or above
- Plus type 2 diabetes
- Or high blood pressure
- Or obstructive sleep apnoea
Use our BMI calculator to check whether your BMI falls within the eligible range.
How We Built These Tools
Every calculator and guide on myweightcheck is built with accuracy and transparency in mind. Our BMI calculator uses the standard WHO formula with NHS-aligned category thresholds. Our GLP-1 projections are modelled on published clinical trial data from SURMOUNT and STEP studies.
All data stays on your device. We don't require sign-ups, and we don't store your health information on any server. Your progress tracker saves data locally in your browser using localStorage, so only you can see it.
We're based in the UK and our tools are designed specifically for UK users — supporting stone & lbs by default, referencing NHS guidelines, using NICE-approved medication data, and linking to GPhC-registered pharmacies.
Frequently Asked Questions
Common questions about BMI, weight loss medications, and our free UK tools.
Is Mounjaro subscription available on the NHS in the UK?
Yes, Mounjaro (tirzepatide) is available on the NHS through specialist tier 3 weight management services following NICE approval. You need a GP referral and availability varies by region with potential waiting lists. It's provided free at point of use but may take several months to access. Private subscription options are also available through GPhC-registered pharmacies.
How much does a Mounjaro subscription cost in the UK?
Private Mounjaro typically costs £129–£320 per month depending on your dose. NHS access is free, but may involve long waiting lists. Costs vary by provider and whether you choose automatic monthly refills or pay-per-prescription. Always confirm pricing with your prescriber or pharmacy before starting.
What is a Mounjaro KwikPen and how often do I need to order it?
A KwikPen is a pre-filled injection pen containing four weekly doses of Mounjaro. You inject once weekly, so each pen lasts one month. You'll need to reorder or refill monthly. Unopened pens must be stored in the fridge at 2–8°C in the original carton. Your prescriber or pharmacy will manage refills.
Can I switch between NHS and private Mounjaro prescription?
Switching between NHS and private prescription requires stopping treatment with one provider and starting with another—you cannot hold both simultaneously. Your new prescriber may need to reassess your eligibility and restart you at the lowest dose (2.5 mg). Discuss any transition with your current prescriber before making changes.
How long does it take to reach the maximum Mounjaro dose?
Mounjaro dose titration typically takes 18–20 weeks to reach the maximum 15 mg dose. You start at 2.5 mg and increase to 5 mg, 7.5 mg, 10 mg, 12.5 mg, and 15 mg—spending a minimum four weeks on each dose. Some people may stop escalating at a lower dose if they experience side effects or achieve their goals earlier.
Ready to take control of your weight loss journey?
Start with a free BMI check, explore your GLP-1 options, or begin tracking your progress today. No sign-up. No cost. Just results.